High-protein, low-carb, no fat. Or how about as much as you can eat with the addition of some miracle product that inexplicably expels the excess from the system?

As most of us grow steadily larger, many weird and wonderful diets have become the ones we are told are the next sure thing - think the Atkins diet, the cabbage soup diet, the grapefruit diet and the South Beach diet. Yet weight gain, obesity and their related problems, such as diabetes and heart disease, continue to soar in the West.

Nutritionist Dr Rosemary Stanton says the only realistic way people will lose weight and keep it off is by eating good, healthy food and exercising. ''There are no miracles in weight loss,'' she says.

Stanton has been working with the federal government's National Health and Medical Research Council on the recent update of its dietary guidelines. The bad news is no surprise: there are no quick fixes.

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''If people just cut down on junk food - we've found that junk food and drinks contribute more than 40 per cent to an average child's daily intake, and 36 per cent to that of an adult - there's a lot of wriggle room,'' she says.

So what of the more established diets, the ones most people wanting to lose weight might be tempted to try? Pulse has followed four people on four different popular diets. They were:

The CSIRO total wellbeing diet: This is a low-fat, higher-protein, nutritionally balanced structured eating plan, with recommended recipes and exercise.

The Weight Watchers regime: In this eating plan every food item is assigned points according to protein, carbs, fat and fibre, and dieters eat within a daily points allowance.

The Dukan diet: Conceived by French neurologist Dr Pierre Dukan, it has four phases, from the first seven days, when dieters eat only protein, to the final phase, in which only protein is eaten one day a week for life.

The 5:2 Diet: This is based on intermittent fasting. Dieters eat normally for five days a week, then consume 500 calories or less for the other two non-consecutive days.

Experts have mixed views about the ability of these diets to strip weight off in a healthy, sustainable way.

Stanton says that while the CSIRO diet has been studied by scientists, she is concerned about the amount of red and processed meat it recommends. It's the same with the Dukan diet, which is also ''ridiculously low in carbs. That's not really a diet you should follow for any length of time,'' Stanton says.

The 5:2 diet has one advantage in that it might remind people what it's like to go hungry, but, generally, it's no good if its followers simply gorge on bad food the rest of the time.

As for Weight Watchers: ''That's fairly well balanced, but its greatest asset is that it gives people support, which is much cheaper than paying a dietitian.''

The Heart Foundation doesn't endorse any particular diet because individuals are all so different, nutrition manager Barbara Eden says. ''But we are concerned about particular diets as they leave out essential food groups, so people miss out on some macro- and micronutrients and won't have enough things like iron and calcium and dietary fibre,'' she says.

For those reasons, the Dukan Diet and the 5:2 Diet are the ones Eden favours the least. She says people should try to aim to eat from the five food groups every day.

While Weight Watchers diet plans tend to be well balanced and include physical activity, and the CSIRO has a lot of scientific backing for its diet, Eden still has concerns.

''So many people go on diets and then immediately put the weight back on - or more - when they come off them,'' she says. ''There's no substitute for changing eating patterns slowly over time to make a permanent, sustainable difference.''

NICHOLA MIDGLEY

33, speech therapist,Hills District, Sydney

5:2 diet

''I'm a bit of a foodie, making my own cheese and sausages, and I have my own food blog, niccooks.com, but it got to the stage where I was a bit overweight.

The intermittent fast seemed like a diet that would suit my lifestyle: I can't exercise as I have a back injury and it meant I'd still be allowed to eat well most of the time.

So for two days a week, I just ate fewer than 500 calories, which equated to a slice of toast for breakfast, a bowl of home-made soup, a couple of rice crackers and a tomato, and fish and vegies for dinner.

People assume you'll binge on the other days, but you tend to keep your portion sizes down as you don't seem to need as much food.

I'm a pretty stubborn person and when I set my mind to do something, I see it through. But the hardest thing was other people thinking you're strange for doing something like this. They found it hard to comprehend.

I did the diet for four months, lost 11 kilograms and went from a size 14 to size 10.

Surprisingly, I didn't feel bad at all at first. I think I had fat reserves to burn. It was only when I got to the 10-kilogram loss that I felt a bit weak.

I've lost all the weight I needed to so I'm not doing it now, but if I ever put on a few kilos, it's a simple quick-fix to go back to it.''

GEORGINA RUSSELL

43, aged-care worker, Brighton, Melbourne

Dukan diet

''The Dukan was the latest craze and, after a lot of other diets, I liked the sound of losing a lot of weight quickly, plateauing and then maintaining your weight.

But it was very hard at first. You had to give up sugar, and as someone who ate stacks of chocolate, I went through a sugar withdrawal, which was hideous. Giving up carbs such as bread was hard, too.

For the first stage, I just basically ate tins of tuna and meat. It was like being a cat for a week. I'd sit there chewing and thinking how miserable my life was.

I had no energy and I felt lethargic, so I couldn't exercise either. I felt a bit out of it, too. You have a metallic taste in your mouth and you can see people backing away from you because your breath smells.

But in the first two weeks, I lost three kilograms, so it does work. You shrink, you really do. Your face gets thinner and your stomach and waist get smaller.

I persuaded my boyfriend to do it, too. We'd sit looking at each other, chewing and saying, ''Don't we have something more interesting to do? He lost five kilograms in the first three days but then said he was dying and struggled to a chemist, who told him to eat a plate of green vegetables to get some electrolytes into his system. We can laugh about it now.

I did it for two months but didn't lose any more weight. Ultimately, I couldn't live like that.''

JANE DEVENISH-MEARES

42, criminal forensic scientist, Mornington Peninsula, Victoria

CSIRO total wellbeing diet

''I'd put weight on as I wasn't doing any exercise and was working hard - often from 7am to 8pm - without eating anything sensible, then grabbing some Macca's on the way home and going straight to bed.

So I went on the CSIRO diet, eating a lot of protein - meat and dairy products - rather than carbs, such as bread and pasta, and limited fruit. I found myself eating more food than I normally would, sometimes more than I could manage. So it's good for people who get hungry on other diets. But all that meat is expensive.

The main problem was having to read a big book, plan ahead and prepare meals the night before, as you have to weigh everything, such as yoghurt and fruit, and then carry around Tupperware containers all the time. It can feel like death by a thousand cuts when you're trying to maintain a busy lifestyle.

Working at the Victorian Institute of Forensic Medicine, I would never know what time I'd get home and I'd sometimes be called out at 2am to go to a crime scene. You don't have time to weigh yoghurt before you go.

But in 10 weeks, I lost 10 kilograms, went from a size 14 to a small 12, and I felt better in myself with heaps more energy. My migraines also disappeared. It did work, but other diets might involve less homework for equal results.

I wouldn't want to do the CSIRO diet long - term; it doesn't have the flexibility I need.''

DANE SQUANCE

34, horse-industry marketer, North Ryde, Sydney

Weight Watchers

''About three years ago, a photo was taken of me at a family lunch and I was shocked and embarrassed that the person in the photo was me.

I was 149 kilograms and I'd been overweight since childhood. As a kid, it had always been hard, not being picked for team sports or not being able to get through a sports match. As an adult, I'd got into the habit of putting a lot of things on hold until I'd lost weight. I'd pretty much tried every diet.

But as a result of that photo, my fiance, Alyssa, and I decided to join Weight Watchers. Losing weight for our wedding in October 2011 was our short-term goal and, long-term, we wanted to be healthier and perhaps have children.

I think the positive thing about Weight Watchers was that it gave me the tools to learn about losing weight. I learnt about portion sizes and the right food choices. I could eat what I wanted and when I wanted within the points system. I could still eat bad food occasionally but then I'd eat good food to make up for the points blow-out.

Exercise has now also become a huge part of my life and something I enjoy daily.

To be honest, I didn't find it hard. Once you get it into your head what the best options for you are, it gradually becomes second nature.

It took me 50 weeks to reach my goal weight of 90 kilograms, and today I weigh 83 kilograms.